Summer is coming, airplanes are fuller than ever, and the airlines are squeezing every penny they can from passengers.

I now approach the thought of a flight with about as much enthusiasm as I might anticipate same-day surgery. For already weary business travelers, it seems as though each new change in airline policy has been for the worse, not better.

Among them are changes to airline loyalty programs, once an essential calculation in a business traveler’s experience. Many are increasingly losing value. United Airlines last week announced major changes to its MileagePlus program that will diminish the benefits of accumulating miles. Starting in March, “members will earn award miles based on their ticket price, rather than distance flown,” United said.

It’s a complicated formula based on price paid and elite-status level. By linking mileage status to money paid instead of miles flown, United followed a somewhat similar move by Delta Air Lines that will take effect in January. The other major network carrier in the United States, American Airlines, has indicated that it wants to follow suit after it fully integrates its AAdvantage mileage program with that of its recent merger partner, US Airways.

Almost every change is being done with an eye toward extracting more revenue from mileage programs. Airlines are also pushing harder to sharply increase revenue from ancillary fees, especially from what they refer to as the “upselling” of coach tickets.

Anyone who flies regularly knows that paying the base fare doesn’t reliably get you what the airlines now hilariously refer to as a “complimentary” assigned seat. Instead, the airlines are using what they call dynamic pricing to assign a range of additional fees for coach seats.

United, for example, boasted to its shareholders that the “real-time positioning” technology it used to assign extra prices on available seats led to an increase of 15 percent in ancillary revenue in the first quarter of 2014.

This sort of pricing strategy is also drifting into first-class cabins, where unsold seats traditionally were given as upgrades to frequent fliers who had various elite-status levels. Now, some first-class seats not sold at the usual prices as departure approaches are being offered instead to coach passengers at check-in time, at discount prices.

As someone without elite status on any airline, I selfishly welcomed this trend on a recent flight on American Airlines from New Orleans to Dallas on a basic coach ticket. At check-in, a box popped up on my computer offering me a seat in first class for a mere $45 extra. I went for it because I had a checked bag that would have cost me $25 on my coach ticket but would be free in first class. As a result, that first-class upgrade actually cost me $20. Still, in another time, the first-class seat that I bought so cheaply would most likely have been awarded as a free upgrade to a coach passenger who had elite status.

With the summer travel surge coming soon, flights will become even more crowded — if that’s even possible. Already, most flights are flying full on most routes, as indicated by load factors in excess of 87 percent reported for May by United, Delta and American (and 83.7 percent by Southwest).

So we gripe, but we trudge to the airport and line up to fly.

The other day, incidentally, Riaan Manser, a seasoned world traveler, noted the crowding in the skies. “The sky is full of traffic, another telltale sign that we’re near New York City,” Manser tweeted from the Atlantic Ocean on Sunday in the final stage of his journey rowing a small boat from Morocco to New York.

A few days before that, I had emailed Manser asking him for perspective on our proclivity to complain about airlines, which, after all, will fly you from Casablanca to New York for about $1,000 in just over eight hours.

By comparison, the boat trip with his girlfriend of 14 years, Vasti Geldenhuys, will have taken over five months once they arrive in New York this week.

“Columbus was a business traveler, and so am I,” said Manser, a self-described adventurer who once bicycled the perimeter of Africa and wrote a book, “Around Africa on My Bicycle,” about the trip. After the couple had made a brief stop in Miami last week before their last hard row to New York, he told me, “I travel economy, mainly.

“People complain about the eight-hour flight from New York City to London? We spent four months rowing across the North Atlantic,” Manser said from sea via email. He added, in business travel, “the three things we all look for: space, space and more space.” In the boat, space is limited, no upgrades are available and “the restroom is a bucket,” he noted.

“Dinner service has no choices,” he added. But on the other hand, the fresh fish on the daily menu was “better than the best the airlines can serve.”

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